POULTRY ASPERGILLOSIS (FUNGAL PNEUMONIA): EFFECTIVE TREATMENT AND PREVENTION

Aspergillosis (fungal pneumonia) is a common disease in poultry and wild birds. The disease usually does not cause mass mortality like some acute infectious diseases; however, it leads to emaciation, reduced egg and meat productivity, prolonged rearing periods, and forced culling, thereby causing significant economic losses. The disease is particularly severe in young poultry, especially at 1–4 weeks of age, where it can result in high mortality rates. The risk factors, impacts, and control measures of aspergillosis in poultry will be analyzed in detail in this article by Fivevet. 1. Characteristics of Poultry Aspergillosis (Fungal Pneumonia)
Aspergillosis is considered one of the important diseases in poultry. The causative agents are fungi of the genus Aspergillus, which are parasitic and primarily cause infection in the lungs. In addition to the genus Aspergillus, several other fungal genera associated with pulmonary aspergillosis in poultry have been reported, including Penicillium, Paecilomyces, Cephalosporium, Trichoderma, Scopulariopsis, and Mucor. Among these, Aspergillus species are more prevalent than the others.
To date, 73 species of fungi belonging to the genus Aspergillus have been identified; however, the two species most commonly causing aspergillosis in poultry are Aspergillus fumigatus and Aspergillus flavus. Other species may also cause the disease but are less frequently encountered, such as A. terreus, A. glaucus, A. nidulans, A. niger, A. amstelodami, and A. nigrescens.
2. Modes of Transmission and Predisposing Factors for Outbreaks
The disease has been reported in many species, including chickens, turkeys, guinea fowl, pheasants, quails, pigeons, ducks, muscovy ducks, and geese. Poultry can be infected at all ages; however, the disease is usually severe and associated with high mortality in young birds aged 1–4 weeks. Adult poultry typically develop a chronic, prolonged form of the disease.
The disease is also observed in wild birds such as sparrows, parrots, grouse, jungle fowl, pheasants, wild ducks, wild geese, swans, ostriches, and penguins. In these species, the disease usually occurs in a chronic form.
Transmission may occur via eggs; when breeder hens are infected, fungal spores can be transmitted through the eggs, causing chicks to become infected as early as 1–5 days of age. Fungal spores can survive for months to years in feed, farming equipment, housing facilities, and contaminated air within poultry houses, especially under hot and humid conditions, which favor fungal growth.
The disease occurs worldwide but is more prevalent in hot and humid tropical regions, particularly in Africa, Asia, and South America. Outbreaks commonly occur during the hot and rainy seasons. In Vietnam, the disease most frequently occurs from May to August each year.
3. Clinical Signs of Poultry Aspergillosis (Fungal Pneumonia)
3.1. Clinical Signs of Aspergillosis in Chickens
The incubation period in chicks aged 5–7 days is usually 3–6 days, while in adult chickens it is approximately 7–15 days. Affected birds typically show signs of depression, reduced appetite, and respiratory distress. When breathing, chickens often stretch their necks, breathe with an open beak, and produce hoarse vocalizations.
The disease becomes more severe when secondary infections occur, such as Escherichia coli, Mycoplasma, infectious bronchitis (IB), and infectious laryngotracheitis (ILT), causing severe dyspnea, rales, coughing, and gasping sounds described as “O-shaped choking sounds.” Chicks may die within 10–15 days, with a high mortality rate of approximately 50–70%.
If chickens are affected by uncomplicated pulmonary aspergillosis, respiratory signs are usually milder but more prolonged. In adult chickens, dyspnea gradually worsens, and birds may show nasal discharge, progressive weight loss, and hoarse vocalization. Laying hens exhibit a gradual decline in egg production, may lay soft-shelled or immature eggs, and can cease laying altogether if the disease becomes prolonged.
In some cases, chicks show signs of enteritis, including yellow-green diarrhea, which is more commonly observed in young chicks and growers. Adult chickens may suffer from a chronic course lasting 1–2 months or longer, eventually dying in a state of emaciation and severe debilitation.
3.2. Clinical Signs of Aspergillosis in Waterfowl
Ducks are highly susceptible to Aspergillus fumigatus.
The incubation period is 3–7 days in ducklings aged 1–3 weeks and 10–20 days in adult ducks. In many cases, the causative agent of aspergillosis in ducks has been identified as Aspergillus flavus.
Affected ducklings often show poor appetite, lethargy, reduced activity, nasal discharge, and progressively severe dyspnea. In some cases, green or yellow watery diarrhea may be observed. Ducklings may die after 7–10 days, with a high mortality rate of 70–80% among infected birds.
Adult ducks typically exhibit nasal discharge, gradually reduced feed intake, and labored breathing. In particular, female ducks may develop a hoarse voice resembling that of drakes, experience decreased egg production, become emaciated, and may die after 2–3 months due to exhaustion or be culled.
Muscovy ducks and geese usually show clinical signs similar to ducks, including poor appetite, nasal discharge, coughing, wheezing, and prolonged respiratory distress. Facial sinus swelling, hoarse vocalization, and progressive weight loss may be observed, with death occurring due to respiratory failure. 3.3. Clinical Signs of Aspergillosis in Turkeys
Turkeys infected with Aspergillus fumigatus have an incubation period of 3–7 days in birds aged 7–30 days and 10–20 days in adult turkeys. Affected birds typically show poor appetite and reduced activity, followed by respiratory distress, nasal discharge, and ocular discharge. A proportion of cases may develop conjunctivitis (approximately 20–28%).
Young turkeys may exhibit neurological signs (around 15–20%), such as tremors, unsteady gait, and coughing or wheezing at night and in the early morning. Laying hens show reduced or ceased egg production, become progressively emaciated and debilitated, and may die due to exhaustion and respiratory failure. Mortality in turkeys aged 1–2 months can reach 50–60% of affected birds.
3.4. Clinical Signs of Aspergillosis in Wild Birds
The disease can cause pneumonia and airsacculitis in wild ducks, swans, and several other bird species. Respiratory tract lesions have also been reported in pheasants, Japanese quail, ostriches, penguins, and many wild bird species as a result of infection with Aspergillus spp.
4. Lesions Observed on Necropsy
In young poultry such as chickens, ducks, Muscovy ducks, and geese, necropsy findings are generally similar. Creamy-white or greenish fungal colonies may be observed. The areas surrounding the fungal colonies show fibrous inflammation, and in some cases the lungs are adhesive and congested. In young pigeons, fungal growth may be seen on the skin as small yellowish necrotic lesions.
In adult poultry, characteristic lesions are mainly found in the respiratory tract, with fungal colonies of varying sizes—ranging from mung bean– to corn kernel–sized—flattened in shape and white-yellow, green, or dark green/black in color. These lesions are commonly located on the palate, larynx, trachea, and lung surface. The longer the disease duration, the darker the fungal lesions become. The fungal nodules are usually dry and very brittle. Surrounding the fungal foci, there is yellowish-gray necrotic inflammation, along with fibrosis and congestion.
In ducks, lesions are similar, with necrotic nodules approximately 5–8 mm in diameter. Lesions may appear yellow-white when caused by Aspergillus flavus, or yellow-green to gray-green when caused by Aspergillus fumigatus. These lesions are found in the larynx, trachea, on the lung surface, within lung lobes, and in the air sacs.
In turkeys, lesions are similar to those observed in chickens, and fungal nodules may also be present on the cornea, causing ocular swelling and inflammation. Wild birds infected with Aspergillus spp. show lesions similar to those seen in chickens, turkeys, and waterfowl. 5. Diagnosis
Diagnosis of aspergillosis is mainly based on clinical signs combined with characteristic lesions, typically including inflammation of the respiratory tract and the presence of fungal colonies in the bronchi and air sacs, which may also spread to other organs.
To accurately identify the causative agent, fungal culture and isolation can be performed from clinical samples. In addition, enzyme-linked immunosorbent assay (ELISA) methods are applied in some cases to detect Aspergillus infection in poultry.
To shorten diagnostic time and improve accuracy, farmers can collect clinical samples and submit them to Fivelab for specialized testing. Please contact the hotline 0822 120 555 for consultation and support with sample collection to ensure timely disease detection.
6. Prevention of Poultry Aspergillosis (Fungal Pneumonia)
This disease commonly occurs when poultry are exposed to feed and litter contaminated with mold spores. Therefore, controlling litter and feed to prevent fungal growth is the most effective preventive measure, while also helping to reduce the risk of secondary infections.
When mold is detected in the litter, poultry should be moved to a dry area, all contaminated litter should be removed and disposed of, the housing should be thoroughly disinfected, and new, clean litter should be applied before returning the birds. Under no circumstances should poultry be fed mold-contaminated feed.
It is recommended to regularly mix mycotoxin-binding agents into feed, such as Five-Anti Toxin, according to the recommended dosage. In addition, vitamins, minerals, and beneficial microorganisms should be supplemented to enhance flock immunity, such as Five-Aminovit Super, Five-Mix, Five-Caphos, Five-Enzym, Five-Mensong, and Five-Prozyme 5way.
In practical farming conditions, some farms may periodically use antibiotics to treat secondary infections. When applying this approach, antibiotics derived from natural fungal sources should be avoided, and professional guidance is recommended to minimize potential risks. 7. Treatment of fungal pneumonia in poultry
When the disease is detected, birds showing obvious clinical signs should be removed, and preventive treatment should be applied to those without clinical symptoms. At the same time, sources of infection such as mold-contaminated feed or litter must be properly handled. Suspected moldy feed should be eliminated and replaced with fresh feed, and contaminated litter should be replaced with clean, dry bedding.
- Disinfection of poultry houses can be carried out using disinfectants such as Five-Iodine, Five-B.K.G, Five-BGF, Five-Perkon 3S, applied strictly according to the manufacturer’s instructions.
- Antifungal drugs such as Five-NP.10, Five-Funazole may be administered to poultry at therapeutic dosages as indicated on the product labels, continuously for 3–5 days.
- Vitamin A supplementation should be included in the diet.
- To enhance digestion, boost immunity, and support detoxification of the flock, supplements such as Five-Bogama, Five-Orgamin, Five-Lyte Oral, Beta-Glucan.C can be administered. - Along with medication, better flock management is essential, including reducing stocking density, improving house ventilation, and minimizing moisture and dust, in order to help poultry recover more quickly.